This invention relates to a communication apparatus which transmits/receives information with a destination via a communication line and transfers/receives information with a host computer connected as an external device, and to a communication control method therefor.
In a conventional communication system having a communication terminal connected to a host computer, communication is performed when an origination instruction is received from the host computer.
FIG. 26 is a flowchart showing a process procedure for processing an incoming-call by the conventional communication system. FIG. 27 is a flowchart showing a calling process procedure by the communication system.
In case of call origination, when a calling request command is received from the host computer (step S228 in FIG. 27), the communication terminal performs a predetermined communication protocol (step S229) based on calling information received with the command.
In case of incoming-call terminating, the communication terminal performs the communication protocol with a destination side terminal (step S221 of FIG. 26), and transmits/receives data to/from the calling-side terminal. When the communication has been completed, the communication terminal sends a data-transfer start command to the host computer, starts a timer and waits for a response from the host computer (step S222). If a response has been received from the host computer (YES at step S223), the communication terminal transfers the data which was received from the originator side, to the host computer (step S224). The data is processed in the host computer.
However, if no response is received from the host computer (NO at step S223), and the response-waiting timer has timed out (YES at step S226), the received data is deleted or discarded (step S227).
If the communication terminal does not connect to any host computer and no response has been received, or in a case where the communication terminal connects the host computer but it is in busy status due to execution of another application, and no response is received, the communication cannot be completed even though an incoming call has been received. Even if the communication is established, it is probable that the communication terminal cannot process the received information properly. Accordingly, in such cases, the established communication link must be disconnected, or the data received from a destination terminal is not used and deleted, thus resulting in a waste of both communication and information.